Painting medium-density fiberboard

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Old 05-22-06, 12:56 PM
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Painting medium-density fiberboard

I am building a custom-made large bookcase (16 feet wide, 9 feet tall, almost 100 adjustable shelves). I’m using MDF (medium density fiberboard). I am now in the process of painting it. I have primed it using acrylic enamel undercoater from Duron (which accepts water- or oil-based paint, I understand). Given some time/space constraints and for the sake of easier clean-up, I am leaning towards using white semi-gloss latex enamel (Duron Plastic Kote), rather than oil-based paint. Also, I am planning to paint the borders of each shelf in various pastel colors. Questions;

1) Is it OK to use water-based products for a shelving system/bookcase? It’s not going to be a heavily-used piece (it’s not like kitchen cabinets), and the shelves will not be adjusted that frequently. However, I have heard that professionals strongly suggest using oil-based paint.

2) How many coats would you recommend? I am planning 3 coats. I am planning to sand a bit between coats and at the end to have a very smooth surface.

3) Is semi-gloss latex enamel sufficient for durability and protection? Or would gloss / high-gloss be better for durability/”scrubability”? I prefer not to have a shiny finish. At the same time, gloss latex appears to be less glossy than gloss oil-based.

4) In order to make the semi-gloss latex enamel more like a lacquery oil-based enamel paint, would it be a good idea to mix some high-gloss latex based enamel (that does look and feel like a lacquery paint) with my semi-gloss paint?

5) In order to add protection to it, would it be to also put some water-based poly? Would 2 coats be ok? If so, could I just put two coats of paint?

6) It’s going to be hard to paint the borders of each shelves with pastel colors without staining some of the white-painted parts of the shelf. Putting masking tape may be too time-consuming. I was thinking of actually using oil-based paint for such borders – it shouldn’t stain the water-based white paint, and it would give me more time for clean-up. Is that a good idea? If not, how about using some acrylic glazing medium (which retards the drying time of the paint and would allow some time window for clean up)? Or is it that latex enamel is just too porous to allow even a fast cleanup, and masking tape is the only way to go?

Thanks!

Carlos
 
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Old 05-23-06, 03:58 AM
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#1 - oil base dries to a harder finish, waterborne enamels are also acceptable. The problem with latex enamels is they don't dry all that hard and sometimes objects that are set on them will stick.

#2 - 1 coat of primer and 2 coats of finish are usually sufficent.

#3 - see #1, It is true that latex enamels are usually less shiny than their oil base counterpart. I would suggest a satin oil base enamel if you don't want much sheen.

#4 - You can mix different sheens together as long as the base is compatible [latex with latex, oil with oil]

#5 - Latex poly may add additional protection. IMo it isn't necessary if quality paint was used. Since poly has no pigment you still need enough paint under it to fully cover/color the piece.

#6 - I'm not big on masking tape as it can give a false sense of security. The best way is to apply the paint carefully so as not to need any clean up, easier said than done. I would keep a rag handy [possibly damp with thinner] and wipe up an errant paint immediatetly.

hope this helps
 
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Old 05-25-06, 10:38 AM
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marks,
Thank you very much for your reply.
- Carlos
 
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Old 05-25-06, 11:29 AM
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Your'e welcome, anytime
 
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Old 05-25-06, 11:49 AM
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marksr,
Thanks again for your reply. I have decided to just put three coats of the semi-gloss acrylic latex enamel (the third one with some latex extender as to make it flow better, more smoothly and without brush/roll marks). One last question: IF I decide to put water-based poly over the latex enamel, I was thinking of doing so very thinly (as to not create a thick film that can crack) with a rag. Would this be ok? And how long should I wait after the paint and before the poly?
Whatever I end up doing, I will not put any object on the shelves for at least two weeks, to allow them to fully dry.
Thanks
-Carlos
 
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Old 05-25-06, 12:21 PM
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Other than stains or oils I have never used any of the rag on finishes and actually don't really understand how they would work - but then my lack of knowledge is another story

I'm not sure you would need the latex poly but if I were to use it I would thin it with floetrol [maybe a little water], use a good brush and technique to help eliminate brush marks.
 
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Old 05-25-06, 04:16 PM
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Originally Posted by marksr
Other than stains or oils I have never used any of the rag on finishes and actually don't really understand how they would work
You are not alone there buddy
I'm not sure what a rag-on poly is either
Sorry...

I'm not sure where the poly over paint thing is coming from either
But I've had a few people ask about it lately
-not that there's anything wrong with that-it's just curious


maestroperu, I would be surprised if you needed a poly over the enamel, is it an effect you are looking for?...or durability?
 
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Old 05-25-06, 09:32 PM
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slickshift,
I want to use poly to avoid tackiness. I have used an acrylic latex enamel for my bookcase; however, I have read that latex "sticks" to objects placed over it -- I guess I should have used oil-based. Some alarmists say that the paint will remain a bit tacky *forever*. I gather that the use of a clear coat will eliminate the tackiness. However, I am also afraid it may make the whole thing more chip-prone, and also make touch-ups more difficult. Is poly a good solution, given the pros and cons?

I don't really care whether I use a rag or brush -- I just though a rag would lead to a thinner film.

Thanks,

Carlos
Thanks
 
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Old 05-26-06, 03:49 AM
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Originally Posted by maestroperu
I have used an acrylic latex enamel for my bookcase; however, I have read that latex "sticks" to objects placed over it

I don't really care whether I use a rag or brush
Ah, I see
There is a difference between "latex" paint and "acrylic latex enamel" paint

I would be surprised if you had a problem with a good quality (acrylic latex) enamel

If you do decide it needs poly, like marksr says, a quality brush, good technique, and maybe some floetrol
Honestly I don't recommend poly over paint
I'd wait and see if sticky-ness was a problem first
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Old 05-26-06, 09:50 PM
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Thanks for your reply. IF I do decide to use poly over the paint to avoid potential tackiness, I will plan to use Minwax polycrilic over the (third and final coat of) my acrylic latex. Given the size of the bookcase (16 feet by 9 feet: 14 equidistant vertical parts of 9 feet tall each, more than 100 shelves, each of 1 squared feet), If I go for poly, I will plan to do the following:
1) Wait a week after the final coat of acrylic latex.
2) Lightly sand the shelves.
3) Apply one coat of Polycrilic to the shelves,
4) Wait a month before loading shelves with books.

I will not apply polycrilic to the vertical parts -- they won't hold books anyway, plus it will be a pain to touch-up if need be. (If I get chips/cracks to the poly on the shelves, it will be very easy to touch-up them, since the shelves are small). Also, I will apply only one coat of polycrilic -- I don't look forward to coating 100+ shelves twice, plus I am not going for appearance, just more protection.

Does it sound like a reasonable plan? Will just one coat of poly be insufficient, and a second coat will be necessary?

Thanks again.
 
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